Technical Field
The present disclosure relates to a method of producing a nitride fluorescent material, the nitride fluorescent material, and a light-emitting device using the same.
Description of Related Art
Light-emitting devices including combinations of a light emitting diode (hereinafter may be referred to as “LED”) and a fluorescent material have been increasingly applied as lighting apparatuses and backlights for liquid crystal displays, etc. For example, in the case where such light emitting devices are used in a liquid crystal display, a fluorescent material of a narrow half bandwidth is desired to provide a wider range of color reproducibility.
Examples of such a phosphor include a red light-emitting phosphor of SrLiAl3N4:Eu (hereinafter may be referred to as “SLAN phosphor”). For example, Patent Literature (PTL) 1 and Non-Patent Literature (NPL) 1 (Philipp Pust et al. “Narrow-band red-emitting Sr[LiA3N4]:Eu2+ as a next-generation LED-phosphor material” Nature Materials, NMAT4012, VOL 13 September 2014) disclose SLAN phosphors having a narrow half bandwidth of 70 nm or less and having a peak fluorescence wavelength near 650 nm.
As disclosed in NPL1, a SLAN phosphor is, for example, produced such that powder of raw materials including lithium aluminum hydride (LiAlH4), aluminum nitride (AlN), strontium hydride (SrH2), and europium fluoride (EuF3) are weighed in a stoichiometric ratio so that Eu is 0.4 mol % and mixed. The mixture is placed in a crucible and calcined in a mixed gas atmosphere of hydrogen and nitrogen under atmospheric pressure at a temperature of 1000° C. for two hours.